Moisture is a well known problem for electrical systems.
The first issue with moisture and electrical systems is that water may short out an electrical circuit.
However, another problem caused by moisture is
corrosion.
Electrical systems in outdoor or non sheltered installations are particularly exposed to conditions that tend to cause physical defects in the system.
For example,
extreme temperature fluctuations, extremes in humidity, water intrusion,
fouling by debris and being disturbed by animals are just a few of the problems that can affect an electrical system deployed outdoors.
When an electrical system is deployed in a remote location, access is generally limited by the remoteness of that location, and so an electrical system tends to lack regular examination and maintenance.
When combining a lack of maintenance with an outdoor installation, electrical systems can suffer a high
failure rate.
However, as a practical matter, an electrical system cannot be completely sealed because the system needs maintenance, updating, repair and the like.
Permitting moisture in the form of humidity or liquids to contact the
metal conductors of the electrical system can cause the
metal circuits to corrode and eventually fail.
And
galvanic corrosion is a well known issue that arises when dissimilar metals are able to exchange ions via direct contact or a liquid pathway.
This can particularly be a problem where connectors, cables, wires, traces, solder joints and the like are made from different metals and are exposed to moisture.
Systems for sheltering the electrical system from the elements can offer some respite from the water and prolong the useful life of an electrical system, but even with such enclosures, the electrical system will still fail at some point.
Another issue with such electrical system installations is condensation.
The shed or component
enclosure may protect the electrical system from
snow, hail leaves and the like, but it cannot practically be sealed against changes in temperature or humidity.
It is the changes in temperature and humidity that lead to problems with condensation and the introduction of moisture within the electrical system's component housings.
Attempts to monitor the conditions have been made by electronic humidity sensors but with little long term success.
The issue with electronic humidity sensors is that the humidity sensing element must remain exposed to the elements and is prone to
corrosion itself.
This sensing element
corrosion also tends to occur faster than most other electrical system components because the sensor has no protection from the elements, while other electrical system components have some sheathing or enclosure based protection.
This difference in weather protection tends to cause the humidity sensor to corrode and fail faster than other, more protected electrical components.
The
disadvantage to a chemical indicator such as a desiccant is that a user must observe the desiccant's color at a particular time to determine the instantaneous humidity level.